Empire lasting for about 1,000 years, from about 400 BCE to 600 CE, in today's central Libya (Fezzan), principally along the still existing Wadi al-Ajal.Relatively little is known of the empire, because little excavation has taken place in the large tracts of ruins. Another potential source of information are the abundant rock paintings, even if many of these depict lifestyles prior to the rise of the empire itself.The capital, Garama, was located at today's Germa, about 150 km west of modern-day Sebha. An earlier capital, Zinchecra, was located not far from the later Garama. The ruins consist of numerous tombs, water tunnels, forts and cemeteries.The decline of the Garamantian Empire and its civilization is connected to negative impact of the climatic change. What is desert today was fairly good agricultural land, enhanced through irrigation, 1,500 years ago.The Garamantian Empire represented a great challenge to the Romans. It never gave in to Roman power, although the coastal zones of today's Libya did. Despite this, Herodotus reported that they had no weapons of war, and did not know how to defend themselves. Although this was during the early stages of the empire, some kind of military system must have been developed, even if we do not have any proof of it.